Tib., sangs rgyas lnga: Five Purified and Awakened Ones
In the drawing, the central blue plane represents the sambhogakaya realm, indicating the five directions in which the above Buddhas manifest as visionary beings representing the all-encompassing Adibuddha (here symbolized by the three-dimensional sphere).
Each of these Buddhas represents one of the five families and each also has a so-called 'spiritual son' (or two): Bodhisattvas who represent the active energy of the respective Sambhogakaya Buddha by way of their (Nirmanakaya) manifestations and incarnations.
There are other collective Sanskrit names in use for these five deities: tathagathas and jinas. Also, there are other systems of organization - mostly with Vairocana changing positions (center/east) with Akshobhya.